I already open a specific topic but perhaps developers are more looking in this one to get idea…

I miss an app to do SMS group. To permit people without internet to be able to be part of a group communication.
All group app that I know use MMS (need internet) or directly internet.
(The only-one that I fund doing this is “groupme” a Microsoft app )

I detected the Playstore App “Quizduell” I wish an App which use the Question/Answer Data from https://www.kwdb.ch and generate something similar.
This Database seems has Problems at moment to get enough maintenance.

Beside the normal Questions which allows fighting against Friends, I like the Quality Questions this app asks about the Duell Questions. That improve the Questions also.

For my part, I miss on F-Droid an application to manage the contents of one or more domestic freezers.
Many cool features could be added: different forms of sorting, alerts when the deadline of consumption approaches, barcode scanner, partial recovery of the product sheet on openfoodfacts.org, etc.

Well, I primarily use Keep to draw, and there are basically no other vector based drawing note apps. Certainly no FOSS ones :c The only issue I have with Keep is that I can’t export stuff later, and I have to take a screenshot or PNG rendered by google on their website, but it’s still detailed enough to extract SVG from PNG in Inkscape.

That being note app is useful because of cataloging of my ideas for later use Categories and such, attaching notes to drawings etc.